Correct file formats: RGB and CMYK

If you’re starting out as a designer, one of the most confusing aspects of computer-based graphic design is the difference between RGB and CMYK color modes, as well as the difference between various file formats.

Although this subject is brought up countless of times in the design blogosphere, I believe it was never explained in a way that’s simple, easy to remember and most importantly, easy to work with.

So here we go.

Understanding and using the RGB color model
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Simply put, RGB color model is a technology for mixing (R)ed, (G)reen and (B)lue light in order to produce any imaginable color. This technology and color mixing process is used by all computer screens and electronic devices.

How this truly works is beyond the scope of this article. In short, your computer screen, laptop, cellphone and most other electronic devices are small miracles capable of showing millions of colors just by mixing various intensities of red, green and blue light.

Your computer screen is coloring each pixel in this image by mixing different intensities of red, green and blue light. For example, certain purple pixels in this image are rendered by combining RGB values shown on the right.

As a designer, you have direct control over this process because you can manually adjust the RGB intensity of each pixel in order to get the color you want — the higher the values, the brighter the colors (just like turning on more lights gives you a brighter room).

You should always design in RGB color mode if your final artwork is going to be used on computer screens or digital devices. This includes:

user interfaces

websites

web banners

icons

any other design piece intended for electronic use

All major design applications offer you instant color model presets for web and other types of RGB artwork.

Check if your document is properly set up for RGB work

When creating a new file, make sure that the new document window shows proper settings:

For Illustrator: select “Web” in the New Document Profile dropdown

For Photoshop: select “Web” in the Preset dropdown, then make sure the resolution box shows 72

For CorelDRAW: select “Web” in the Preset destination dropdown

Deliver final RGB files to client

While JPEG is the format of choice for submitting design entries, the final RGB files should be delivered according to this checklist:

Website layouts: PSD (zipped)

User interfaces: PSD (zipped)

Icons: PNG (include original PSD or AI file if requested by client)

Web banners: PNG, GIF (include original PSD or AI if requested by client)

Never use TIFF, EPS, PDF or BMP file formats to deliver RGB artwork, as they serve a completely different purpose. Learn more on the different file formats by checking out File Formats Explained: PDF, PNG and More.

Understanding CMYK printing
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Using RGB is great if your design will be used on screen. But if there is even the slightest chance of your artwork is being printed, you need to create files in CMYK color mode.

Each tone and color in the business card above was mixed by layering different amounts of cyan, magenta , yellow and black ink. The illustration on the right shows the ink mixture for a specific hue of green.

Unlike computer screen, a printer cannot use light to paint colors on paper, which is why it has to use the next best thing — plain ole’ ink.

All desktop and professional printers mix four different ink colors — (C)yan, (M)agenta, (Y)ellow and (K)ey (Black) which is abbreviated as CMYK. These four colors can be mixed together in varying amounts and produce thousands of different shades and hues on paper.

But as you can imagine, mixing CMYK inks is very different than mixing RGB lights. For example, if more lights are added to RGB it produces brighter colors where as adding more ink in CMYK produces darker colors. In RGB, White is defined with the maximum value of each color channel (R:255,G:255,B:255), while in CMYK mode it’s defined as a complete lack of color (C:0%,M:0%,Y:0%,K:0% ).

RGB can give you very bright and nice colors (after all, it’s a light show) that are impossible to produce using inks. If you forget about this, you might end up with a great online design that looks quite dull when printed.

This logo was created in RGB, but its colors are so bright they cannot be reproduced using CMYK inks. Bad idea.

Luckily, you don’t have to worry about this because your design application can imitate the colors of CMYK printing system and create the appropriate files.

Check if your document is properly set up for CMYK print work

Follow these guidelines when creating documents for print:

For Illustrator: On the New document window, make sure to select “Print” in the New Document Profile dropdown.

For InDesign: On the New document window, make sure to select “Print” in the Intent dropdown.

For CorelDRAW: On the New document window, select “Default CMYK” in the Preset Destination dropdown.

For Photoshop: On New document window, select RGB as color mode and set resolution to 300 dots per inch. Immediately after that, turn on CMYK color imitation (View > Proof colors).When done, convert your final document to CMYK color mode (Image > Mode > CMYK > Flatten) then save the file under a different name. Use this file to finalize your print design in Illustrator, InDesign or CorelDRAW. Note that you can also create CMYK files right from the start (just pick CMYK mode on the New document window), but this will prevent you from using certain effects and functions.

Why 300 DPI?

Besides CMYK inks, an important piece of the printing world is the image resolution, expressed in DPI or PPI (which stands for Dots Per Inch or Pixels Per Inch, which is the same thing).

Printers are different creatures than computer screens. While computer screens need 72×72 pixels to show a 1×1 inch image (72 DPI), printers need at least 300 pixels for each inch in order to show the image in the same size and quality.

Although it’s quite large on the screen, the image on the left will print well only as 1” x 0.76” thumbnail because quality printing requires at least 300 DPI.

That’s why creating a 10×10 inch image at 300 DPI in Photoshop will give you a file measuring 3,000 pixels in width and height — very large on screen but just 10×10 inches of quality print.

Therefore, always create files at 300 DPI resolution if you intend to print them. Make sure to remember that resizing an existing image to 300 DPI is not an option as it will only duplicate existing pixels and give you a blurry image — you have to create artwork with enough pixels from the very beginning.

If you want to check at which size your existing photos and other artwork can print well, simply divide their pixel dimensions by 300. For example, a 1280 x 1024 pixel photo will print well at 4.26 x 3.42 inches — anything larger than that will make it blurry

Note: you don’t have to worry about DPI for vector objects created in Illustrator or CorelDRAW — they print well at any size. The DPI relates only to bitmap images traditionally handled by Photoshop.

Deliver correct CMYK printing files to client

The industry standard for CMYK file delivery is a properly prepared PDF:

For Illustrator: Go to File > Save As > “Adobe PDF” from the Save As Type dropdown box. A window will open prompting you to select PDF settings — all you need to do is select “Illustrator Default” from the Adobe PDF preset dropdown box, then hit Save. This will produce PDF file which is both ready for print and editable by Illustrator.

For InDesign: Go to File > Adobe PDF Presets > Press quality. A window will appear allowing you to adjust many prepress settings, but you can safely hit Export and In Design will create a proper PDF file for professional printing.

For CorelDRAW: Go to File > Publish to PDF , then pick “Prepress” from the PDF preset dropdown box. This will produce print ready PDF file which can be opened by any Adobe application as well.

In addition to this PDF file, you may export your design to other file formats requested by client (usually EPS or AI), but make sure to communicate that PDF is basically all they need because it can be opened and used by virtually any design software.

Wrapping up
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Understanding the difference between RGB and CMYK is an essential piece of design every designer must know.

The bottom line is simple: while RGB uses light to mix colors on screen, CMYK uses ink to mix them on paper. These are very different processes but easily managed by your design application if you create the files with proper settings.

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The author

Peter Vukovic is a seasoned designer & creative director with 10 years of experience in worldwide advertising agency.
He is a proud member of the 99designs community. You can view his 99designs profile here.

Through my experience of being on both sides of the lifecycle of Design and Printing; 15 years and still ticking…
This article does a great job explaining the color theory of design. However, I will need to make notes that it is also up to the printer that is being used for proper color. Most commercial printers use a RIP program that processes colors for the printer. Most RIP programs will convert RGB -> its own CMYK mixture. This being said building a file using RGB vs CMYK is a moot point. PANTONE swatches from a book will only get a designer so far.
Having a PANTONE Chart printed off a printer will be far more valuable for the design process. The chart from the actual printer will show the variation that printers have in the commercial industry. To further note that the operator of the printer if experienced can and most times will modify the balance of ink distribution of each color based on the files being printed.
My suggestion is find a good company that is willing on creating a good bond and relationship with the design group or individual. And understand how the printer produces the print via RIP or however they create the final product. You’ll find more value in knowing if there is a consistent shift from the paper being fed through the printer. How best to set up the bleed margin for the variations of cutting devices. And most importantly how the color is created.

I am working at a print shop, doing t-shirts and some of the files cannot have a clolor in the background. I save them as a png and the color mode goes to RGB, which isn’t good for print. How do I save an illustrator file with no background to a CMYK format?

HI Peter, Great Article, very informative Thanks!
Quick Question, I use PSD to create my web designs, but when I use “web” as the preset I am unable to change the dimensions to any other.. Is there a way around it?

Hi there,
just found this great article while looking for the best way how to convert CMYK colours into RGB colours. I’m a graphic designer, mainly working in the field of corporate design, including of course designing logos. I always create the logo for print, means in CMYK, but most clients also want to use them online (websites, social networks, etc), means I they need a RGB version too. My question: What is the best/safest/most convenient way to convert CMYK colours in RGB colours?

Sorry, but your article does nothing but disseminates a totally wrong concept about CMYK being the “good”, professionals’ preferable format for printing and prepress.
Actually you can use CMYK in artworks to be sent to the prepress service bureau just in 2 cases:

1. You are absolutely sure about the ICM profile the printing machine is calibrated for,
2. You use some special colors, where avoiding halftoning and registration problems are much important than color fidelity, e.g. Red text = 100% Magenta + 100% Cyan.

In all other cases there might be a risk to have your CMYK objects converted back to RGB (actually Lab) and then again to CMYK in order to match their workflow’s ICM profile.

Modern RIP workflows are usually able to make the RGB->CMYK conversion much better than the host process, so why you would work in a format which has a narrower gamut and much worse post processing capabilities? Repeat, unless you know exactly the (eventually proprietary) ICM used by the service bureau in question. But I hardly think lots of “beginner” designers would be able to ask for this specific ICM.

Finally, I found the explanation that agrees with a Color Management course I had for 2 weeks. The teacher, with 25 years of experience on the printing industry, kept telling us: never work with or convert to CMYK mode unless you have full control of the entire calibrated workflow, including the printing machines. But I’ve searched through dozens of videos, sites and blogs and they keep saying “work on CMYK if the end-result is to be printed”. Thanks.

Elise

Feb 21 2012

This! As an illustrator working in Photoshop, CMYK makes layer blend modes behave differently and painting in CMYK feels very unnatural if you have learned to paint in RGB as most digital artists have.

I also learned that it’s best to work in RGB to give anyone down the line the maximum number of colour to convert from. Just remember to keep previewing your work in CMYK to spot potential those out-of-gamut areas and avoid major disappointment when your beautiful fluorescent artwork all turns the same mucky colour.

Tania Willis

Feb 21 2012

Very helpful article – thank you. I found it whilst trying to discover why my PSD illustrations ( often with a white background) have poor resolution & a lot of background noise when I use the the ‘Save For Web’ setting on PSD to prepare for display on facebook / tumblr etc.I usually use .jpg. Shoud I be using png? I’d love to know your tips for the best way to format PSD artwork for optimal image quality?

I have a name card with raster image. I have set my AI document to Print mode which is in CMYK. But then when I embed an image, and when I save it to PDF, it looked washed out like your sample font. What should I do?

Hello, when I checked my dpi is set to 300. Then I go to flatten image and proceed to image>mode>cmyk and i save it as a png… It seems everything goes fine until I check the file information and it shows the colorspace RGB … Can you help kindly help me? Thank u

Best guess is, foxit reader does not support CMYK. Same thing has happened to me when i open CMYK images in google’s picasa in the past.
It’s obvious that illustrator CMYK preview would be the closest to the actual print result.

María

Feb 21 2012

But when I create a CMYK file in Corel in CMYK I see it well in Foxit but no in Adobe reader 8(
The theme of CMYK drives me crazy. I never know what is going to be printed 🙁

Pushez

Feb 21 2012

Well, If you have the correct CMYK settings in the design program (illustrator, Coreldraw, Photoshop…) i wouldn’t worry about the differences in PDF readers, the print result would be very close the one seen on the program.

María

Feb 21 2012

Thank you. Anyway I will try to do a test print to be sure.

Pushez

Feb 21 2012

yep, that’s probably the best way… 🙂

Hp Singh

Feb 21 2012

hi…
i am designing a logo for a client and it’s going to be used in web development as well as for printing. In such situation can u please tell me how to set a document and how to retain the true colors. As we know that RGB colors looks different in CMYK format.

It must have been obvious, but somehow missed my attention that by saving for web you are entering the RGB color realm, so no wonder Photoshop will produce an RGB image even if the file you worked on used a CMYK color mode. I noticed that Illustrator will produce a CMYK file, through “Save for web” if the project was using CMYK color space 🙂

300 ppi is overkill if you’re printing with a 120 line screen or less. Although hard drives and RAM are cheap these days, we used to have to worry about excessive resolution because it would bring a computer to its knees. Also, excessive resolution actually results in “softer” images.

Adobe used to have great examples of this in the (printed) Color Printing Guide that they included with their graphics programs. They explained why 1.5 to 2 times the screen frequency is the maximum resolution needed in an image. So if you’re printing on newsprint with a 100-line screen frequency, 200 ppi is plenty.

There isn’t an exact conversion method as they are two printing processes (ink vs. light, additive vs. subtractive). Additionally, the color profile will often depend on the specific printer and the ink they use, so that’s a good place to start.

Kaelyn McParland

Feb 21 2012

Okay I am now a little confused, in Illustrator I made the profile “Web” so it’s 72 ppi and RGB and I am still getting the message that I don’t have a valid file? I am at a loss as to what else I am supposed to do here

Peter, I just learned of your company through a friend. He is excited that his contribution to your program provides financial assistance for the design artist now working on his logo. The person working on his logo has no idea why various file formats are needed. She is using .jpg for everything, yes everything to include digital layouts. The work is a sad mess! Are 99designs.com artists’ educated on the purpose and role CMYK and RGB have re: file formats?
Thanks, Peter!

All designers are required to upload a variety of file types, all of which are listed in the contest brief. This help article and additional resources on the blog are also made available to designers.

If your friend is still having issues, 99designs support will get them the files they need!

Sandy

Feb 21 2012

Great article, I stumbled upon it in my despair because of some things going on in our office. Our R&D department is thinking about saving rendered product images in png instead of tiff, because it saves them precious time and space on the server.
From these tiff files we make artwork for our printed media, we convert to high resolution jpg’s for print purposes as well, low resolution jpg’s for our website and png files to be placed on backgrounds in online pdf product leaflets.
My initial reaction (I’m the one who designs all printwork and online exposure, allthough I did not study for it…which is the reason I feel a little lost and hope for some help from you pro’s) was that png is merely suitable for online use. But on the other hand, Indesign converts al RGB items to CMYK when I export to PDF.

I consulted a collegue that has a DTP background. He also adviced against but he made my despair even a bit greater: he was surprised that I used high res jpg’s in Indesign without converting them to psd first and change the rgb mode to cmyk. That is the way he learned to do it. As our catalogue never showed imperfections that made me think as well: obviously the Indesign conversion of all rgb colors to cmyk when exporting to pdf went well so why change my way of working? That said then working with png’s in Indesign should’t be too big of a problem either…am I right?

Can someone give me advice that helps me to convince against or for this change form tiff to png? Can I make good artwork (to be printed) from a png file? Is it just a matter of making the PNG large enough and 300dpi?

What you state about DPI are just old myths. Digital screens have a wide range of varying PPI values (obviously, since there are retina screens and non-retina, for example), and 300 DPI for print is arbitrary nowadays. You can print at any DPI value you like, it’s just a matter of how dense you print the pixels.

Hey. If you’re still checking this for comments, I have a question. If I save my CMYK file to PNG, it automatically converts it to RGB… Is anything “bad” about thaat or should I always convert CMYK to RGB then save as a PNG? Inquiring minds want to know. Great article BTW.

CMYK is typically used for print files whereas PNG is a raster based format that is typical used for photos and web, not for printing. Feel free to read more about different file types here.

Michael Lane

Feb 21 2012

I’m just getting started in the digital medium. Right now I am using Procreate and was excited to start designing. However this article makes it look like Procreate is not sufficient for what I would need to send out, is that true?